Users Guide

Option Number and Description
Domain Name
Server
Option 6
Species the domain name servers (DNSs) that are available to the client.
Domain Name Option 15
Species the domain name that clients should use when resolving hostnames via DNS.
IP Address Lease
Time
Option 51
Species the amount of time that the client is allowed to use an assigned IP address.
DHCP Message
Type
Option 53
• 1: DHCPDISCOVER
• 2: DHCPOFFER
• 3: DHCPREQUEST
• 4: DHCPDECLINE
• 5: DHCPACK
• 6: DHCPNACK
• 7: DHCPRELEASE
• 8: DHCPINFORM
Parameter Request
List
Option 55
Clients use this option to tell the server which parameters it requires. It is a series of octets where each
octet is DHCP option code.
Renewal Time Option 58
Species the amount of time after the IP address is granted that the client attempts to renew its lease with
the original server.
Rebinding Time Option 59
Species the amount of time after the IP address is granted that the client attempts to renew its lease with
any server, if the original server does not respond.
End Option 255
Signals the last option in the DHCP packet.
Assign an IP Address using DHCP
The following section describes DHCP and the client in a network.
When a client joins a network:
1. The client initially broadcasts a DHCPDISCOVER message on the subnet to discover available DHCP servers. This message
includes the parameters that the client requires and might include suggested values for those parameters.
2. Servers unicast or broadcast a DHCPOFFER message in response to the DHCPDISCOVER that oers to the client values for
the requested parameters. Multiple servers might respond to a single DHCPDISCOVER; the client might wait a period of time
and then act on the most preferred oer.
3. The client broadcasts a DHCPREQUEST message in response to the oer, requesting the oered values.
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Dynamic Host Conguration Protocol (DHCP)